How many variables are needed to specify the state of moist air (assuming thermo. equilibrium)?
Do these 3 variables suffice?
{p, T, theta} -- no (why? redundant, no moisture variable)
{q, RH, T} -- no (why? redundant, no pressure variable)
{qtot, p, h} Under what conditions? (saturation)
Which of (a)-(f) are preserved when 1) no phase change occur and 2) phase changes do occur?
a) enthalpy b) dry static energy c) potential temperature d) moist static energy e)entropy f) equivalent potential temperature
What are the effects of moisture on lifted-parcel buoyancy?
we considered 5
Which has more CAPE, reversible or pseudoadiabatic ascent? Discuss.
What makes the difference between (T_rho-T_env) and (T_v-T_env) curves?
A: condensate loading
In which part of the atmosphere shows the maximun virtual temperature effect and condensate loading effect?
A: virtual effect : at low levels where parcel has the most water vapor
loading effect: at upper level where the parcel has the most condensed water.
Q: What is buoyancy reversal and why is it important to cumulus dynamics? A: When saturated, cloudy air mixes with unsaturated air, the density of the mixture can be greater than the density of either component. The most dense mixture is the one in which just enough dry air is added to evaporate all the cloud water. In terms of cloud dynamics, this means the average density (or buoyancy) of a finite volume of air is different if that volume contains folded filaments of cloudy and dry air vs. if those filaments have truly mixed at the molecular level. Numerical averaging and instrument response times tend to act like mixing, so both models and slow-response observations of cumulus clouds may give an inaccurate picture if the true buoyancy in turbulent, incompletely mixed clouds.
Q: What 2 terms are in the w equation for a convective updraft? A: Buoyancy and a PGF involving the pressure perturbations p' (deviations from a hydrostatic reference state).
Q: What is the role of p', and what 2 main terms can it be broken into? A: p' is the pressure field necessary to enforce mass continuity (i.e. to prevent mass convergence or divergence, in an incompressible or Boussinesq flow) in the presence of a field of forces that may be strongly divergent/convergent. Therefore, p' is like the inverse laplacian of the divergence of the other forces. Those other forces are buoyancy, whose divergence is dB/dz, and advection of momentum, whose divergence involves 2 parts: a "spin" term (vorticity squared, which drives a negative p') and a "splat" term (deformation squared, which drives a positive p'). So there is a buoyancy-driven p', and a dynamic p', and the dynamic p' can be further broken down.
Q: In a supercell, the dynamic p' has two main parts of importance. What are they? A: 1. The spin term for vertical vorticity, producing low p' where vortex tubes in the environmental shear are tilted to make mesocyclones, and 2. the 'obstacle effect' p' due to vertical momentum transport in a vertically sheared horizontal environmental flow. It makes a high p' on the upshear side of an updraft, where the oncoming flow crashes into the momentum from below that has been brought up in the updraft.
Q: What are the anelastic and Boussinesq approximations? A: Taking density to be a constant (Boussinesq) or reference function of height only (Anelastic). It simplifies the PGF (not a product of 2 variables any more so derivatives don't proliferate terms y the Chain Rule). Also the continutity equation is simplified, which simplifies the jump from advective form to flux form.
Q: What are the energetics of a 3D (whole fluid) convecting fluid body in the Boussinesq approximation? A: The integral [bQ] (correlation of heating and buoyancy) creates potential energy. The integral [bw] (rising of buoyant air) converts that to kinetic energy. The integral [F•U] (flow opposed by friction) removes kinetic energy.
Thermo and buoyancy
How many variables are needed to specify the state of moist air (assuming thermo. equilibrium)?
Which of (a)-(f) are preserved when 1) no phase change occur and 2) phase changes do occur?
a) enthalpy b) dry static energy c) potential temperature d) moist static energy e)entropy f) equivalent potential temperature
What are the effects of moisture on lifted-parcel buoyancy?
Which has more CAPE, reversible or pseudoadiabatic ascent? Discuss.
Describe contributions to parcel buoyancy by moisture and name which has the biggest contribution.
(You can find the answer from http://www.rsmas.miami.edu/users/bmapes/teaching/MPO663_2011/Class4.html)
What makes the difference between (T_rho-T_env) and (T_v-T_env) curves?
A: condensate loading
In which part of the atmosphere shows the maximun virtual temperature effect and condensate loading effect?
A: virtual effect : at low levels where parcel has the most water vapor
loading effect: at upper level where the parcel has the most condensed water.
Q: What is buoyancy reversal and why is it important to cumulus dynamics?
A: When saturated, cloudy air mixes with unsaturated air, the density of the mixture can be greater than the density of either component. The most dense mixture is the one in which just enough dry air is added to evaporate all the cloud water. In terms of cloud dynamics, this means the average density (or buoyancy) of a finite volume of air is different if that volume contains folded filaments of cloudy and dry air vs. if those filaments have truly mixed at the molecular level. Numerical averaging and instrument response times tend to act like mixing, so both models and slow-response observations of cumulus clouds may give an inaccurate picture if the true buoyancy in turbulent, incompletely mixed clouds.
Q: What 2 terms are in the w equation for a convective updraft?
A: Buoyancy and a PGF involving the pressure perturbations p' (deviations from a hydrostatic reference state).
Q: What is the role of p', and what 2 main terms can it be broken into?
A: p' is the pressure field necessary to enforce mass continuity (i.e. to prevent mass convergence or divergence, in an incompressible or Boussinesq flow) in the presence of a field of forces that may be strongly divergent/convergent. Therefore, p' is like the inverse laplacian of the divergence of the other forces. Those other forces are buoyancy, whose divergence is dB/dz, and advection of momentum, whose divergence involves 2 parts: a "spin" term (vorticity squared, which drives a negative p') and a "splat" term (deformation squared, which drives a positive p'). So there is a buoyancy-driven p', and a dynamic p', and the dynamic p' can be further broken down.
Q: In a supercell, the dynamic p' has two main parts of importance. What are they?
A: 1. The spin term for vertical vorticity, producing low p' where vortex tubes in the environmental shear are tilted to make mesocyclones, and 2. the 'obstacle effect' p' due to vertical momentum transport in a vertically sheared horizontal environmental flow. It makes a high p' on the upshear side of an updraft, where the oncoming flow crashes into the momentum from below that has been brought up in the updraft.
Q: What are the anelastic and Boussinesq approximations?
A: Taking density to be a constant (Boussinesq) or reference function of height only (Anelastic). It simplifies the PGF (not a product of 2 variables any more so derivatives don't proliferate terms y the Chain Rule). Also the continutity equation is simplified, which simplifies the jump from advective form to flux form.
Q: What are the energetics of a 3D (whole fluid) convecting fluid body in the Boussinesq approximation?
A: The integral [bQ] (correlation of heating and buoyancy) creates potential energy. The integral [bw] (rising of buoyant air) converts that to kinetic energy. The integral [F•U] (flow opposed by friction) removes kinetic energy.